The invention relates to a process for manufacturing a film card duplicate. Furthermore the invention relates to two different film card cameras for carrying out said process.
Film card duplicates are required in a considerable number of cases. A drawing office with an aperture card installation cannot benefit fully from it unless the information contained in the cards-usually drawings, parts lists and patent specifications-reaches the respective destinations as quickly as possible after the cards are produced. For that reason sets of cards are made from every original in quantities as demanded by the distribution list. The average number in the majority of drawing offices is 3-5 cards per document. Only a few of the larger concerns, e.g. the motor industry have a considerably higher distribution. As an example: Opel normally produce 30 duplicate cards from each drawing, VW over 60 and BMW even up to 70.
As a rule a set of cards consists of one original card and two to four diazo duplicate cards. Producing such a set requires a camera and a duplicator needing two separate operations. More importantly, two different kinds of film, each processed differently, are being used: In the original card the silver film stores the image with high resolution and even density. Duplicate cards are then copies from the original card whereby a loss in quality can occur, depending on the quality of the duplicating device and of the diazo film. Those who do not want to risk a loss of quality in their duplicate cards, partly only noticeable after several years, will produce their card sets entirely on silver film cards. Many companies, especially in the USA and in England, have for years specified multiple exposures by rollfilm camera of each document onto silver film with subsequent mounting on cards. Although this produces a better quality negative, it is time-and labor-consuming, and the risk of imprecise mounting remains.
Rational application of graphic data storage (GDS) on film aperture cards in technical offices requires the means for producing duplicate cards at any time, even from single cards. When the original drawings are destroyed or when, as often happens with satellite archives, the entire archive consists of film cards, these have completely taken the place of the originals. Duplicate cards are, therefore, a very important part of GDS.
To date the duplicate cards have been manufactured on the basis of the diazo process in the form of diazo card duplicates by means of diazo copiers. Diazo copiers consist of an ultraviolet contact-exposure unit, a NH.sub.3 processing unit and of the associated isolating devices and transporting means. Diazo card duplicates have the shortcoming that a quick loss in density occurs when frequently used in reading or magnifying devices or when improperly stored, e.g., when subjected to ultraviolet light or too high temperatures. This results in a considerable deterioration of their suitability for being read and copied. They then become unusable for many purposes, e.g., for automatic magnification.
When installing microfilm systems, e.g., for storing drawings, the expensive diazo copies have to date had to be bought in addition to the film card camera. This constitutes an additional capital expenditure and the introduction of a technologically different working process. Insufficient use is made of this additional expenditure when only a small number of card duplicates is required per day.
Recently increasing use is made of the computer aided design (CAD) computer when generating drawings. CAD cameras with cathode rays or a laser beam render it possible to expose a microfilm by means of the rays or the beam on the basis of a computer routine in such a manner that a computer-generated drawing is stored on the microfilm after processing is completed. Also these CAD cameras generate microfilm cards, card duplicates of which have as a rule to be manufactured.